Knife sharpener and edge straightener

ABSTRACT

A knife sharpener and edge straightener including an elongate, flexible band having a fine grain abrasive surface on one side thereof, a frame for mounting the band in a generally V-shape, and a compression spring within the frame for maintaining the band under tension while permitting the band to yield when a knife is applied thereto. A knife is manipulated into contact with the band in the same manner as a butcher&#39;&#39;s steel not only to straighten the edge but to sharpen it as well. The band is sufficiently flexible to permit the angle and lateral position of the sides thereof to conform to the angle and force at which the knife is applied thereto.

United States Patent 1 Bonapace [451 Mar. 18, 1975 KNIFE SHARPENER AND EDGE STRAIGHTENER [76] Inventor: Mario J. Bonapace, 4329 Miriam PL, La Mesa, Calif. 92041 [22] Filed: May 14, 1973 [21] Appl. No.: 360,330

[51] Int. Cl 824d 17/00, B24d 15/00 [58] Field of Search 51/358-361, 51/391-393; 76/81.1, 81.2

[56] References Cited UNITED STATES PATENTS 2,151,450 3/1939 Suhayda 76/81.2

2,189,307 2/1940 Bierna t. 51/391 X 2,415,367 2/1947 Paviovic t l 51/392 X 2,430,060 11/1947 Lamb et al 51/361 2,493,852 l/1950 Bonkowski 51/391 X Primary E.\'aminerOthell M. Simpson Attorney, Agent, or Firm-Philip M. Hinderstein [57] ABSTRACT A knife sharpener and edge straightener including an elongate, flexible band having a fine grain abrasive surface on one side thereof, a frame for mounting the band in a generally V-shape, and a compression spring within the frame for maintaining the band under tension while permitting the band to yield when a knife is applied thereto. A knife is manipulated into Contact with the band in the same manner as a butchers steel not only to straighten the edge but to sharpen it as well. The band is sufficiently flexible to permit the angle and lateral position of the sides thereof to conform to the angle and force at which the knife is ap- 4 plied thereto.

8 Claims, 6 Drawing Figures BACKGROUND OF THE INVENTION 1. Field of the Invention.

The present invention relates to a knife sharpener and edge straightener and, more particularly, to a novel tool which may be used not only to straighten the edge of a knife but to sharpen it as well.

2. Description of the Prior Art.

When using a knife, two effects combine to limit its cutting ability. In the first instance, the edge will readily bend when striking a hard object so that normal movement of the knife does not bring the edge thereof in contact with the surface to be cut. Secondly, and independently of bending of the edge, the edge eventually becomes worn, losing its sharpness and ability to cut.

In those situations where knives are used extensively, constant attention must be given to both of these problems. Therefore, butchers, restaurateurs, and other users of knives typically do two things to keep their knives in proper working order. In the first instance, a steel is used, but only to maintain the edge straight. By running both sides of the knife edge alternately into contact with opposite sides of the steel, at exactly the proper angle, the fine edge of the knife may be straightened prior to making a cut. However, eventually the knife loses its fine edge from the constant bending thereof while cutting and from the process of straightening the edge with a steel. The constant bending of the edge results in its breaking off from the blade so that continued use'of a steel is of no help as there is no fine edge to straighten. Therefore, the user must periodically use a handstone or some other grinding device to sharpen the knife or must have it sharpened for him. After this has been done, the user can once again use a steel to keep the fine edge straight. Even then, however, if the user does not use the steel at the proper angle or with equal pressure, he can turn or bend the cutting edge to one side, thus not getting the full benefit from the fine edge of the knife.

The sharpening of knives is generally done on a belt grinder. However, a considerable amount of skill is required to properly manipulate the knife into contact with the grinder. If the grinder is used improperly, it is easy to ruin the blade or its temper and a good knife is an expensive item. Therefore, since butchers, restaurateurs, and other users of knives typically do not have the experience necessary to properly use a grinder, they typically send the knives out to be sharpened by an expert grinder. Since this must be done on a regular basis and frequently, it is a generally expensive proposition.

SUMMARY OF THE INVENTION According to the present invention, these problems are effectively minimized by providing a combination knife sharpener and edge straightener. A knife is manipulated into contact with the present tool in the same manner as a butchers steel to maintain the edge straight and keep the knife in proper working order for the life of the knife. However, with the present design, while the edge is being straightened, it is being sharpened as well so that the edge will last essentially for the life of the knife. Furthermore, the present tool is constructed so that it is essentially impossible to damage the edge of the knife regardless of how improperly the knife is applied thereto. The present tool includes a band which is sufficiently flexible to permit the angle and lateral position thereof to conform to the angle and force at which the knife is applied thereto so that a knife holds its shape and taper until it is completely worn out. This has not been possible with any other device heretofore.

Briefly, the present knife sharpener and edge straightener comprises a partially hollow handle having a pair of ears extending laterally from opposite sides thereof, an elongate rod, one end of the rod extending into the handle and being movable relative thereto, a spring positioned within the handle for applying an axial force to the one end of the rod, an elongate flexible band having a fine grain abrasive surface on one side thereof-the opposite ends of the band being connectable to the ears of the handle, and a guide connected to the other end of the rod for conducting the center of the band around the other end of the rod, with one side facing outward, thereby compressing the spring and placing the band under tension. A knife is manipulated into contact with the band in the same manner as a butchers steel not only to straighten the edge but to sharpen it as well. However, contrary to the case with a butchers steel, the angle and pressure at which the knife is applied to the present tool is not critical.

OBJECTS It is therefore an object of the present invention to provide a knife sharpener and edge straightener.

It is a further object of the present invention to provide a novel tool which may be used not only to straighten the edge of a knife but to sharpen it as well.

It is a still further object of the present invention to provide a knife sharpener and edge straightener including an elongate flexible band which is sufficiently flexible to permit the angle of the sides thereof to conform to the angle at which a knife is applied thereto.

It is another object of the present invention to provide a knife sharpener and edge straightener including a thin, relatively narrow, elongate, flexible band having a fine grain abrasive surface on one side thereof, such band being mounted under tension in a generally V- shape.

Still other objects, features, and attendant advantages of the present invention will become apparent to those skilled in the art from a reading of the following detailed description of the preferred embodiment constructed in accordance therewith, taken in conjunction with the accompanying drawings wherein like numerals designate like parts in the several figures and wherein:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a knife sharpener and edge straightener constructed in accordance with the teachings of the present invention, showing the manner in which a knifeis manipulated into contact therewith;

FIG. 5 is an enlarged perspective view of the guide means of the present knife sharpener and edge straightener; and

FIG. 6 is a sectional view of a portion of the handle of the knife sharpener and edge straightener of FIG. 2, showing another manner of connecting the opposite ends of the band thereto.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, there is shown a knife sharpener and edge straightener, generally designated 10, for use in straightening and sharpening the edge 11 of a knife 12. Broadly speaking, knife sharpener and edge straightener includes a thin, relatively narrow, elongate, flexible band 13 having a fine grain abrasive surface on one side thereof, frame means, generally designated 14, for mounting band 13 in a generally V- shape with the abrasive surface facing outward, and tension means 15 for maintaining band 13 under ten- S1011.

More particularly, frame means 14 includes a partially hollow handle 16 having a pair of ears 17 and 18 extending laterally from opposite sides thereof, at one end thereof. According to a preferred embodiment of the invention, handle 16 is made in two sections 20 and 21, ears l7 and 18 being made integral with one end of section 20. Section 20 has a first bore 22 extending partially thereinto from the one end thereof and a second, increased diameter bore 23 positioned coaxially with bore 22, bore 23 extending to the other end of section 20 of handle 16. For reasons which will appear more fully hereinafter, bore 23 has a non-round crosssectional shape, a square shape being shown in FIG. 3.

Section 21 of handle 16 has a bore 24 therein to receive a portion of section 20, the length of bore 24 in section 21 being equal to the length of the portion of section 20 which extends thereinto so that the other end 25 of section 20 contacts the base 26 of bore 24 in section 21. The outside surfaces of sections 20 and 21 are continuous and have any suitable shape consistent with the handle of a tool. For example, the end 27 of section 21 may have opposed recesses 28 and 29 therein to receive the opposite ends of a ring 30 which may be used to hang knife sharpener and edge straightener 10.

Frame means 14 also includes an elongate rod 32 which is mounted coaxial with and movable relative to handle 16. More specifically, rod 32 has a diameter which is slightly less than the diameter of first bore 22 in handle 16 so that one end 33 of rod 32 may extend through bore 22 and be freely movable relative thereto. End 33 of rod 32 terminates in a head 34 which has a diameter greater than the diameter of bore 22 but less than the diameter of bore 23, head 34 being positioned within bore 23. Therefore, the movement of rod 32 relative to handle 16 is limited to the movement of head 34 within bore 23. Furthermore, head 34 has the same cross-sectional shape as bore 23, as shown in FIG. 3, thereby preventing rotation of head 34 relative to bore 23 and rotation of rod 32 relative to handle l6.

Tension means 15 preferably comprises a spring positioned within bore 23, between base 26 thereof and head 34 of rod 32. Thus, spring 15 applies an axial force to end 33 of rod 32 biasing rod 32 vertically upwardly as viewed in FIG. 2.

Frame means 14 mounts band 13 in a generally V- shape, within the opposite ends of band 13 being connectable to ears 17 and 18 on handle 16. Ears 17 and 18 include continuous, planar upper and lower surfaces 36 and 37, respectively. The outer ends of ears l7 and 18 have recesses 39 and 40 therein, the widths of which are slightly greater than the width of band 13. This permits the opposite ends of band 13 to extend from upper surface 26 to lower surface 37 while preventing lateral motion thereof. Furthermore, each of ears 17 and 18 has a pair of parallel, spaced slots therein, car 17 including slots 41 and 42 and ear 18 including slots 43 and 44. Slots 41-44 are parallel to each other and to recesses 39 and 40. Furthermore, slots 41 and 43 are equally spaced on opposite sides of rod 32, as are slots 42 and 44. Finally, ears l7 and 18 have curved recesses 45 and 46, respectively, in lower surfaces 37 thereof, the center of curvature of recesses 45 and 46 being coplanar with recesses 39 and 40, respectively.

The opposite ends of band 13 may be connected to ears 17 and 18 in one of two possible ways. In the first instance, the ends of band 13 may terminate in clamps 48 which would rest within recesses 45 and 46 thereby securing the opposite ends of band 13 beneath cars 17 and 18. For this purpose, clamps 48 may be generally cylindrical members having a radius of curvature equal to the radius of curvature of recesses 45 and 46. Clamps 48 may be connected to the ends of band 13in any suitable manner. One possibility is to cut a narrow slot 49 in clamps 48, the width of slot 49 being less than the thickness of band 13. Then, a groove 50 may be cut.

in the abrasive surface of band 13 to provide an area which is thinner than the width of slot 49. With such a configuration, clamp 48 may be slid onto band 13 with groove 50 positioned in slot 48. It has been found that with such a technique, it is essentially impossible to remove band 13 from clamp 48 by applying an axial force thereto.

Alternatively, and as shown in FIG. 6, the ends of band 13 may be connected to cars 17 and 18 without the expedient of clamps 48. More specifically, the ends of band 13 may be conducted through recesses 39 and 40, from upper surface 36 to lower surface 37 and then conducted back through slots 41 and 43, from lower surface 37 to upper surface 36. Finally, the ends of band 13 are conducted through slots 42 and 44, from upper surface 36 to lower surface 37, providing a secure connection.

Frame means 14 further comprises a guide 51 connected to the other end 35 of rod 32 for conducting the center of band 13 around end 35 of rod 32. Guide 51 has a wedge-shaped outer surface 52 around which band 13 is conducted and a pair of tabs 53 and 54 to prevent band 13 from slipping off of surface 52'. Finally, guide 51 has a bore 55 extending partially thereinto from the base 56' thereof for receiving end 35 of rod 32. The diameter of bore 55 is slightly greater than the diameter of rod 32 to permit rotation of guide 51 relative to rod 32.

Band '13 preferably comprises a length of cloth with a fine grain abrasive bonded to one side thereof witha suitable resin material. For present purposes, the grain should be fine, preferably from grit to 240 grit.

OPERATION The present tool 10 does the job of both a steel and a knife sharpener. As discussed previously, a steel does not sharpen a knife, it only straightens the edge thereof, but only if the knife is properly applied to the steel. The present tool not only straightens the edge, but sharpens it as well and knife 12 can be applied to tool at any angle without the possibility of ruining edge 11.

The assembly of knife sharpener and edge straightener 10 is a relatively simple matter. With all parts separated, end 35 of rod 32 is fed into bore 23 and then into bore 22 in section 20 of handle 16, rod 32 being moved axially until head 34 is seated within bore 23. With end 25 of section 20 held upward, spring is dropped into bore 23. Section 21 is then lowered onto section until end 25 contacts base 26. The tolerances with which sections 20 and 21 are made are such that an interference fit is established, preventing disassembly of sections 20 and 21. Furthermore, rod 32 is held in its fully extended position with an axial force applied to head 34 by spring 15.

Guide 51 is then slipped onto end 35 of rod 32 and band 13 is connected to frame means 14. One end of band 13 would be connected to one of ears 17 and 18, in either of the two manners discussed previously, and the center of band 13 would be conducted over surface 52 of guide 51. The other end of band 13 would then be connected to the other of ears 17 and 18 so as to slightly compress spring 15. This places band 13 under tension, holding the opposite sides thereof taught between ears l7 and 18 and guide 51. Furthermore, the spacing between recesses 39 and 40 in ears 17 and 18 is greater than the width of guide 51 whereby band 13 is held in a generally V-shape with the ends spread apart and the opposite sides tapering towards each other, reaching a point of minimum separation at guide 51.

Knife sharpener and edge straightener 111 is now ready for use. As shown in FIG. 1, handle 16 is grasped with one hand and the handle of knife 12 is grasped with the other hand. Knife 12 is now manipulated into contact with band 13 in the same manner as a knife is used with a steel. Both sides of knife edge 11 are manipulated alternately into contact with the opposite sides of band 13, the base of knife 12 first contacting band 13 adjacent guide 51 and the two hands being brought together while moving knife 12 away from band 13 so that the end of the stroke finds the tip of knife 12 adjacent ears 17 and 18.

What is most significant to note is that guide 51 is rotatable relative to rod 32 so as to permit rotation of the center of band 13 relative to the opposite ends thereof. Furthermore, band 13 is sufficiently flexible to permit such rotation. Thus, the angle of the sides of band 13 readily conforms to the angle at which knife edge 11 is applied thereto. In other words, regardless of the angle at which edge 11 of knife 12 is applied to band 13, the angle of band 13 will conform to that angle and properly straighten and sharpen edge 11. On the other hand, it has been found preferable to prevent rotation of rod 32 relative to handle 16. In other words, if bore 23 and head 34 were round, there would be too much ofa tendency for guide 51 to rotate and this has been found to be undesirable.

it is also most significant to note that spring 15 permits axial movement of end 35 of rod 32 toward handle 16. Thus, if either side of band 13 is forced towards rod 32, band 32 simultaneously slides across surface 52 of guide 51 and compresses rod 32 into bore 23. In other words, band 13 adapts its lateral position as a function maintains the tension on band 13 essentially constant and prevents damage to edge 11 if too great a force is applied by theuser. The result is that it is virtually impossible to improperly use knife sharpener and edge straightener 10 and edge 11 holds its shape and taper until completely worn out.

With knife sharpener and edge straightener 10, the force on edge 11 of knife 12 is equal as knife 12 is stroked from the base to the tip thereof. The pressure remains the same because band 13 will yield if knife 12 is applied too hard so that edge 11 maintains its original shape. This also keeps a rounded shoulder on both It can therefore be seen that in accordance with the present invention, the prior art problems are effectively minimizedby providing a combination knife sharpener and edge straightener 10. Knife 12 is manipulated into contact with knife sharpener and edge straightener 10 in the same manner as a butchers steel to maintain edge 11 straight and keep knife 12 in proper working order. However, with the present design, while edge 11 is being straightened, it is simultaneously being sharpened as well so that edge 11 will last for a considerably longer time than if only a steel were used. Furthermore, tool 10 is constructed so that it is essentially impossible to damage edge 11 of knife 12 regardless of how improperly knife 12 is applied thereto. Band 13 is sufficiently flexible to permit the angle and the lateral position thereof to conform to the angle and force with which knife 12 is applied thereto so that knife 12 holds its shape and taper until it is completely worn out.

While the invention has been described with respect to a preferred physical embodiment constructed in accordance therewith, it will be apparent to those skilled in the art that various modifications and improvements may be made without departing from the scope and spirit of the invention. Accordingly, it is to be understood that the invention is not to be limited by the specific illustrative embodiment, but only by the scope of the appended claims.

I claim:

- 1. A knife sharpener and edge straightener comprisa partially hollow handle having a pair of ears extendsurface on one side thereof, the opposite ends of 4 said band being c'onnectable to said ears on said handle; and

guide means connected to the other end of said rod for conducting the center of said band around said other end of said rod, with said one side facing outward, thereby compressing said force applying means and placing said band under tension, said force applying means permitting axial movement of said other end of said rod toward said handle in the presence of additional tension applied to said band.

2. A knife sharpener and edge straightener according to claim 1 wherein a knife is manipulated into contact with said band in the same manner as a butchers steel, wherein said guide means is rotatable relative to said rod, and wherein said band is sufficiently flexible to permit the angle of said band to conform to the angle at which said knife is applied thereto.

3. A knife sharpener and edge straightener according to claim 2 wherein said force applying means permits axial movement of said other end of said rod toward said handle and movement of said band toward said rod so that said band adapts its lateral position as a function of the tension with which said knife is applied thereto.

4. A knife sharpener and edge straightener according to claim 1 wherein a knife is manipulated into contact with said band in the same manner as a butchers steel and wherein said force applying means permits axial movement of said other end of said rod toward said handle and movement of said band toward said rod so that said band adapts its lateral position as a function of the tension with which said knife is applied thereto.

5. A knife sharpener and edge straightener according to claim 1 wherein said axial force applying means comprises:

a spring positioned between said one end of said rod and an internal surface of said handle.

6. A knife sharpener and edge straightener according to claim 1 wherein the spacing between said opposite ends of said band is greater than the width of said guide means whereby said band is spread apart at the ends thereof and the opposite sides thereof taper towards each other, reaching a point of minimum separation at said guide-means.

7. A knife sharpener and edge straightener according to claim 1 wherein said handle has a first bore extending partially thereinto from one end thereof and a second, increased diameter bore, positioned coaxially with said first bore, at the inner end thereof, said second bore terminating internally of said handle, wherein said elongate rod has a diameter which is less then the diameter of said first bore, wherein said elongate rod has a head attached to said one end thereof, said head having a diameter greater than said first bore but less than said second bore and being positioned within said second bore, thereby preventing removal of said rod from said handle, and wherein said force applying means comprises a spring positioned within said second bore, in contact with said head on said one end of said rod.

8. A knife sharpener and edge straightener according to claim 7 wherein said second bore and said head on said rod are non-circular in shape to prevent rotation of said head and said rod relative to said second bore and said handle, respectively. 

1. A knife sharpener and edge straightener comprising: a partially hollow handle having a pair of ears extending laterally from opposite sides thereof; an elongate rod, one end of said rod extending into said handle and being movable relative thereto; means for applying an axial force to said one end of said rod; an elongate flexible band having a fine grain abrasive surface on one side thereof, the opposite ends of said band being connectable to said ears on said handle; and guide means connected to the other end of said rod for conducting the center of said band around said other end of said rod, with said one side facing outward, thereby compressing said force applying means and placing said band under tension, said force applying means permitting axial movement of said other end of said rod toward said handle in the presence of additional tension applied to said band.
 2. A knife sharpener and edge straightener according to claim 1 wherein a knife is manipulated into contact with said band in the same manner as a butcher''s steel, wherein said guide means is rotatable relative to said rod, and wherein said band is sufficiently flexible to permit the angle of said band to conform to the angle at which said knife is applied thereto.
 3. A knife sharpener and edge straightener according to claim 2 wherein said force applying means permits axial movement of said other end of said rod toward said handle and movement of said band toward said rod so that said band adapts its lateral position as a function of the tension with which said knife is applied thereto.
 4. A knife sharpener and edge straightener according to claim 1 wherein a knife is manipulated into contact with said band in the same manner as a butcher''s steel and wherein said force applying means permits axial movement of said other end of said rod toward said handle and movement of said band toward said rod so that said band adapts its lateral position as a function of the tension with which said knife is applied thereto.
 5. A knife sharpener and edge straightener according to claim 1 wherein said axial force applying means comprises: a spring positioned between said one end of said rod and an internal surface of said handle.
 6. A knife sharpener and edge straightener according to claim 1 wherein the spacing between said opposite ends of said band is greater than the width of said guide means whereby said band is spread apart at the ends thereof and the opposite sides thereof taper towards each other, reaching a point of minimum separation at said guide means.
 7. A knife sharpener and edge straightener according to claim 1 wherein said handle has a first bore extending partially thereinto from one end thereof and a second, increased diameter bore, positioned coaxially with said first bore, at the inner end thereof, said second bore terminating internally of said handle, wherein said elongate rod has a diameter which is less then the diameter of said first bore, wherein said elongate rod has a head attached to said one end thereof, said head having a diameter greater than said first bore but less than said second bore and being positioned within said second bore, thereby preventing removal of said rod from said handle, and wherein said force applying means comprises a spring positioned within said second bore, in contact with said head on said one end of said rod.
 8. A knife sharpener and edge straightener according to claim 7 wherein said second bore and said head on said rod are Non-circular in shape to prevent rotation of said head and said rod relative to said second bore and said handle, respectively. 